Using this controller can be designed a speed controller regardless of the load. The electronic speed regulator can be used to control speed of drilling machine as the load grows, tcem Drilling of the machine decreases, while the current increases.
During positive half cycle of supply voltage, C2 is charged through R1 and D1 until the capacitor voltage is equal to the Zener voltage of the circuit to T1. T1 circuit is made with adjustable Zener voltage Zener is determined by adjusting P1.
The motor is not connected in the usual place at the beginning of the circuit, but after thiristor (SCR) Th1. Ignition time of SCR is thus determined by the difference between the Zener voltage and tcem of the motor. If the motor encounter a thiristor will "ignite" faster.